The Monterey Shale oil deposits span 1,750 square miles, but the petroleum is deep underground, trapped in dense rock. Methods such as fracking would bring environmental concerns and no guarantees.

TAFT, Calif. — This two-stoplight town was built on petroleum, and residents here never miss a chance to pay tribute.

A 38-foot monument to wildcatters stands downtown; locals brag it's the tallest bronze sculpture west of the Mississippi. Every five years, the city throws an "Oildorado" festival. There's even a beauty pageant in which young women dubbed "the maids of petroleum" vie to be crowned queen.

It's all an homage to the bustling days when Taft boasted two giant oil fields and Standard Oil Co. of California was headquartered there. The oil giant left in 1968, jobs dried up, and today the Kern County town is saddled with high unemployment and memories of past glory days.

That could be about to change.

Residents are betting on a second boom from oil trapped miles underground in dense rock formations. It's part of what's called theMonterey Shale, where oil deposits span 1,750 square miles through Southern and Central California.

"Everyone and their dog would be working if they find that oil," said Joe Gonzalez, 53, who began toiling in the oil fields around Taft three decades ago as a roustabout. "It's a huge deal for Taft."

But a key question is: Could these modern-day wildcatters actually squeeze oil out of the rock?

Some believe technology that can reach previously inaccessible oil means it's just a matter of time; others are convinced it's an over-hyped promise.

Oil companies have begun exploring the Monterey Shale underneath towns like Taft that have survived on oil for a century.

More than 15 billion barrels of oil, or two-thirds of the continental United States' total deep-rock deposits, is estimated to be locked in the Monterey, according to the U.S. Energy Information Administration. Extracting it could mean enormous wealth if oil prices stay around $97 a barrel, and could pump billions of dollars into the local economy.

The much smaller Bakken shale formation in North Dakota has fueled a boom that has driven unemployment in the state down to 3.3%, the nation's lowest. Taft's unemployment rate is 13.3%.

But the process is slow going.

"It's not like the old days where you put a straw into the ground, you get a gusher and you dance around," said Tupper Hull, spokesman for the Western States Petroleum Assn., an industry lobbying group. "It's a very complicated process."

Los Angeles-based Occidental Petroleum and Venoco Inc. of Denver, two of the largest stakeholders in the Monterey, have already drilled exploratory wells.

Federal land leases on the shale are going for $500 per acre at auction, up from $2 to $5 per acre just a few years ago, said Gabriel Garcia of the Bureau of Land Management's Bakersfield office.

Economists say tapping the shale would be a big boost for the Central Valley, which depends heavily on agriculture and petroleum. By 2015, California could see half a million new jobs and $4.5 billion in oil-related tax revenue, according to a USC study.

"It's not the muckety-mucks, the higher-ups, who live here," said Kathy Orrin, executive director of the Taft Chamber of Commerce. "It's the people in cowboy boots and cowboy hats and Wranglers — and they can make a good living in the oil industry."

Around noon in Taft, oil workers in dusty coveralls park trucks outside the few lunch spots in town: the OT Cookhouse & Saloon, where black-and-white photos of California's first gushers line the walls; Jo's Restaurant, where diners sit below painted oil derricks and fields; and a Tex-Mex place.

Rick McCostlin, 45, thinks jobs could come back and revive Taft. Another oil boom might even attract some of the locals who fled to better-paying gigs in North Dakota's oil fields.

"We got a lot of people leaving when it gets slow," said the ponytailed equipment operator, drinking at the OT Cookhouse's bar.

But the hush-hush world of oil is keeping mum about the Monterey.

With billions of dollars at stake, companies setting up shop are reluctant to reveal any information to competitors. Exploring new oil formations is extremely risky — drilling each exploratory well costs millions of dollars, and most never find anything.

Occidental, Venoco, Chevron and a dozen other oil companies either did not respond to or declined requests for comment.

"The best we have is rumor," said Taft Mayor Paul Linder, 55, who was born in the town. "I will tell you that rumor in this area about oil usually turns out to be the truth because it's hard to keep a secret."

Already, even rumors of that huge oil reserve are bringing new prosperity to the city of 9,400. Best Western submitted plans to build a motel. A housing development with 350 homes built by Hillside Terrace Estates is breaking ground in June. And "numerous" restaurant chains have expressed interest in the small oil town, said City Manager Craig Jones.